Refrigeration system



July 14, 1970. R. s. ARNOLD, SR

. REFRIGERATION SYSTEM Filed July 1, 1968 INVENTOR. RICHARD 5.ARNQLD,SR. BY

yaw 5 M6 ATTORNEY.

United States Patent 3,520,146 REFRIGERATION SYSTEM Richard S. Arnold,Sn, De Witt, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., acorporation of Delaware Filed July 1, 1968, Ser. No. 741,621 Int. Cl.F25b 1/00 US. Cl. 62115 4 Claims ABSTRACT OF THE DISCLOSURE Arefrigeration system to simultaneously satisfy an intermediatetemperature cooling load and a low temperature cooling load or tosatisfy either an intermediate temperature cooling load or a lowtemperature cooling load exclusively.

BACKGROUND OF THE INVENTION In a comfort cooling installation to satisfyan air conditioning load, it is common practice to utilize a coolingtower to provide water to condense the compressed refrigerant in thecondenser portion of the refrigeration machine. Cooling towers normallymaintain a water temperature of approximately 95 F. and therefore thecondensing temperature in the machine would normally be approximately105 F. To provide chilled Water to satisfy the air conditioning load,the desired evaporator temperature would ordinarily be maintained atapproximately 35 F. These conditions would give a temperaturedifferential across the machine of 70.

In a low temperature cooling installation where it is desired tomaintain evaporator temperatures around 0 F. and a cooling tower isutilized for condenser cooling, a condenser temperature of approximately105 would be common. These conditions would give a temperaturedifferential across the machine of 105. For economical compressoroperation over this wide temperature range, multiple stage compressorswould be required which add to the cost of the system.

In some instances, both intermediate temperature refrigeration forcomfort cooling and low temperature refrigeration for manufacturingprocesses, food storage, etc., are required. For example, a stadium mayrequire chilled water for air conditioning and a low temperature heatexchange medium for maintaining an ice rink.

SUMMARY OF THE INVENTION This invention relates to a multitemperaturerefrigeration system employing single stage compressors wherein a firstportion of the system is utilized to satisfy a first cooling load and tocondense refrigerant for a second portion of the system which is adaptedto satisfy a second cooling load at a temperature substantially lowerthan the temperature of the first cooling load.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a schematic illustrationof a refrigeration system embodying the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing thereis illustrated a multitemperature refrigeration system for satisfying anairconditioning load and to provide low temperature cooling. Theair-conditioning load is satisfied by a centrifugal refrigerationmachine having a centrifugal compressor 3, an evaporator 5 and acondenser 7. Refrigerant vapor from evaporator 5 is compressed bycentrifugal compressor 3. The high pressure refrigerant vapor from thecompressor is passed through condenser 7 in heat exchange relationshpwith water or other heat exchange 3,520,146 Patented July 14, 1970medium from a suitable source such as a cooling tower 9. The Water fromthe cooling tower is provided to the condenser 7 through line 11 by pump12 and returns to the cooling tower from the condenser through a line13.

Suitable expansion means 15 are provided for regulating the quantity ofrefrigerant passed from the high pressure condenser 7 to the lowpressure evaporator 5. A suitable heat exchange medium such as water ispassed through evaporator 5 in heat exchange relationship with therefrigerant therein and is cooled thereby. The chilled water fromevaporator 5 is circulated by pump 14 through supply line 16 and returnline 18 for satisfying an air conditioning load represented by heatexchangers 19 or any other medium temperature refrigeration load.

A second refrigeration machine 17 is provided to satisfy a lowtemperature refrigeration load, for example, to produce ice for askating rink.

The refrigeration machine 17 employs a centrifugal compressor 20 tocompress low pressure gaseous refrigerant from an avaporator 21 andprovide high pressure referigerant to a condenser 23. Refrigerant ispassed through condenser 23 in heat exchange relationship with thecooled heat exchange medium from evaporator 5 which is supplied tocondenser 23 by pump 14 through line 24. The heat exchange medium isreturned from condenser 23 through line 26 to return line 18. Suitableexpansion means 25 are provided for regulating the quantity ofrefrigerant passed from condenser 23 to evaporator 21. A heat exchangemedium such as inhibited ethylene glycol is passed through evaporator 21in heat exchange relationship with the refrigerant therein and is cooledthereby. The chilled ethylene glycol is circulated by pump 27 throughsupply line 29 and return line 31 to satisfy a low temperaturerefrigeration load such as an ice skating rink 32. Valves 33 and 35 areprovided in lines 16 and 18 respectively to prevent flow of heatexchange medium from evaporator 5 through heat exchangers 19 when thereis no air conditioning demand. Valves 37 and 39 are provided in lines 24and 26 respectively to prevent flow of chilled water from evaporator 5to refrigeration machine 17 when there is no low temperaturerefrigeration requirement.

The disclosed system is especially suited for air conditioning a stadiumand providing refrigeration for an ice ring in the stadium.

In such an installation, the low temperature refrigeration machine couldbe employed for initially producing the ice for the skating rink whenthe stadium is not in use and therefore the air conditioning load is ata minimum. Once the ice is produced the intermediate temperaturerefrigeration machine is capable of handling the normal air conditioningload and the load imposed thereon by condenser 23 for maintaining theice rink.

The disclosed system utilizes standard single stage refrigerationcompressors to provide a staged refrigeration system by employing theexcess capacity of the intermediate temperature refrigeration machine toprovide a low condensing temperature in the low temperature refrigeration machine. This allows the use of a much smaller lowtemperature refrigeration machine, resulting in lower initial andoperating costs for the complete system. Ordinarily, a refrigerationsystem utilized to provide comfort cooling is operated below its ratedcapacity for the majority of the year since the machine must be sized toprovide suflicient cooling for the warmest days of the year when thebuilding is in use. By utilizing this excess capacity to providecondensing water for the low temperature refrigeration system, theintermediate temperature refrigeration machine can be operated nearcapacity year around. Further, the size of the low temperaturerefrigeration machine can be drastically reduced. By operating theintermediate temperature refrigeration system at or near its ratedcapacity the operating eificiency of the machine is optimized.

The disclosed system employs a single compressor to satisfy theintermediate temperature load and a single compressor to satisfy the lowtemperature refrigeration load. It should be understood that a pluralityof refrigeration machines could be used to satisfy the intermediatetemperature refrigeration load and a plurality of refrigeration machinescould be employed to satisfy the low temperature refrigeration load.This would allow a portion of the intermediate temperature refrigerationmachines and the low temperature refrigeration machines to be shut downwhen the refrigeration loads are reduced to provide for more economicaloperation of the system.

While I have described a preferred embodiment of my invention it is tobe understood that the invention is not limited thereto but may beotherwise embodied within the scope of the following claims.

I claim:

1. A refrigeration system to provide multi-temperature refrigerationcomprising:

a first compressor, condenser and evaporator connected in refrigerantflow relationship to cool a low tempera ture heat exchange medium;

means to circulate the cooled low temperature heat exchange medium tosatisfy a low temperature refrigeration load;

a second compressor, condenser and evaporator connected in refrigerantflow relationship to cool an intermediate temperature heat exchangemedium;

means to provide a portion of the cooled intermediate temperature heatexchange medium to satisfy an intermediate temperature refrigerationload; and

means to provide the remaining portion of the cooled intermediatetemperature heat exchange medium to condense refrigerant in said firstcondenser.

2. A refrigeration system according to claim 1 further including pumpmeans for circulating the intermediate temperature heat exchange medium,said means to satisfy an intermediate temperature refrigeration loadincluding:

a supply line communicating between said second evaporator and theintermediate temperature refrigeration load to supply cooledintermediate temperature heat exchange medium thereto,

a return line communicating with said second evaporator to return heatexchange medium from the refrigeration load, said means to condenserefrigerant in said first condenser including:

a second supply line to provide communication between said first supplyline and said first condenser to pro vide intermediate temperature heatexchange medium to said first condenser, and

a second return line communicating between said first condenser and saidfirst return line to return the intermediate temperature heat exchangemedium from said first condenser to said first return line, said pumpmeans being adapted to circulate intermediate temperature heat exchangemedium through said 4 lines to satisfy said refrigeration load andcondense refrigerant in said first condenser.

3. A refrigeration system according to claim 2 wherein said means toprovide a portion of the intermediate temperature heat exchange mediumto satisfy an intermediate temperature heat exchange load includes:

a first shutoff valve in said first supply line and a second shutoffvalve in said first return line to prevent flow of heat exchange mediumto the intermediate temperature refrigeration load, said means toprovide intermediate temperature heat exchange medium to condenserefrigerant in said first condenser including:

a third shutoff valve in said second supply line and a fourth shutoffvalve in said second return line, said third and fourth shutoff valvesbeing adapted to prevent flow of heat exchange medium to said firstcondenser when said first compressor is inoperative.

4. A method for providing multitemperature refrigeration comprising thesteps of:

compressing refrigerant vapor in a first refrigeration cycle,

passing the compressed refrigerant vapor in heat exchange relationshipwith a high temperature heat exchange medium to condense the refrigerantvapor,

passing the condensed refrigerant in heat exchange relationship with anintermediate temperature heat exchange medium to evaporate therefrigerant, thereby cooling the intermediate temperature heat exchangemedium,

utilizing a portion of the cooled intermediate temperature heat exchangemedium to satisfy an intermediate temperature cooling load,

compressing refrigerant vapor in a second refrigeration cycle,

passing the compressed refrigerant vapor in the second refrigerationcycle in heat exchange relationship with the remaining portion of thecooled intermediate temperature heat exchange medium to condense therefrigerant vapor,

passing the condensed refrigerant vapor in the second refrigerationcycle in heat exchange relationship with a low temperature heat exchangemedium to evaporate the refrigerant, thereby cooling the low temperatureheat exchange medium, and

utilizing the cooled low temperature heat exchange medium to satisfy alow temperature cooling load.

References Cited UNITED STATES PATENTS LLOYD L. KING, Primary ExaminerU.S. c1. X.R. 62-175, 510

